As prostaglandin (PG)E.sub.2 agonists, many compounds have been known including PGE.sub.2 per se or its derivatives. However, no compounds which antagonize for PGE.sub.2 or inhibit PGE.sub.2 activity have been known until now.
PGE.sub.2 has been known as a metabolite in the arachidonate cascade. It has been known that PGE.sub.2 has uterine contractile activity, a pain-inducing effect, a promoting effect of digestive peristalsis, an awaking effect, a suppressive effect of gastric acid secretion, a hypotensive activity etc.
To antagonize PGE.sub.2 means to suppress the effects above mentioned, so PGE.sub.2 antagonists are considered to inhibit uterine contraction, to have an analgetic action, to inhibit digestive peristalsis, to induce sleep. Therefor, PGE.sub.2 antagonists are considered to be useful for analgesics, antidiarrheals, sleep inducer or for the preventive of abortion.
To agonize for PGE.sub.2 means to promote the effects above mentioned, so PGE.sub.2 agonists are considered to have a uterine contractile activity, to promote digestive peristalsis, to suppress gastric acid secretion, to lower blood pressure. Therefor, PGE.sub.2 agonists are considered to be useful for abortient, cathartics, antiulcer, anti-gastritis, antihypertensive.